Recent population expansion in the evolutionary history of the Californian anchovy Engraulis mordax

The Californian anchovy Engraulis mordax, a temperate species, may have undergone a process of population disjunction from experiencing post-glacial water heating processes around the tip of the Baja California Peninsula, Mexico about 10,000 b.p. A genetic analysis was performed to test the null hypothesis of genetic homogeneity between the Gulf of California and Southern California, U. S. A., and if this is the case, to estimate the time of haplotype emergence in terms of coalescence. A total of 80 sequences of the mtDNA hypervariable control region of E. mordax captured in the central Gulf of California (n = 40) and Southern California (n = 40) were analyzed. In spite of the large number of private haplotypes, no significant genetic differentiation among sites (FST = 0.0025, p = 0.686) was observed. An unimodal distribution of mismatch frequency between haplotypes indicated a model of rapid expansion in population size that, based on a mutation rate of 3.6% per million years in the control region, indicates a relatively recent nucleotide differentiation time of approximately 61,000 years. This time period corresponds to the late Pleistocene, suggesting population expansions at each locality, followed by the last episode of glaciation, which may have contributed to migration of this temperate-affinity species between two locations and the genetic homogenization. However this unique recent event of gene flow in the evolutionary history of species does not explain by itself the mismatch distribution patterns found

Diseño, construcción y caracterización de un perfilómetro de haz láser

Determinar las propiedades de los materiales nanoestructurados debido a la radiación laser es la degeneración de los plasmones superficiales en nanopartículas metálicas, como las de oro o plata.El maser (Microwave Amplification by Stimulated Emission of Radiation) fue el primer dispositivo para producir radiación electromagnética con propiedades como coherencia, direccionalidad, poca divergerncia y altamente monocromática

Molecular identification of Auxis spp. larvae (Pisces: Scombridae) from the Gulf of California: Solving morphological identification limits

The larvae of the Auxis genus are abundant in the Gulf of California during summer; however, their identification to the species level by morphological methods is a challenge. The goal of this study was to identify A. thazard and A. rochei larvae for first time, through molecular markers using COI sequences of mtDNA, and look for distinctive morphological characteristics between species, mainly in pigmentation patterns. Larvae were obtained by zooplankton tows in 3 oceanographic cruises in the southern Gulf of California and adjacent waters. The presence of A. thazard and A. rochei larvae was genetically confirmed. The sequences of 7 larvae showed genetic divergences lower than 1% when were compared to sequences of A. thazard adults, while 15 larvae showed genetic divergences lower than 2% when where compared to sequences of A. rochei adults. Genetic divergences between both Auxis species were higher than 2%. These results suggest the spawning of both species in the Gulf of California. On the other hand, pigmentation patterns and morphometric characteristics, in all larval stages, did not permit the secure differentiation between species. Thus, the use of molecular identification by COI is recommended to identify Auxis larvae to the speciesThe larvae of the Auxis genus are abundant in the Gulf of California during summer; however, their identification to the species level by morphological methods is a challenge. The goal of this study was to identify A. thazard and A. rochei larvae for first time, through molecular markers using COI sequences of mtDNA, and look for distinctive morphological characteristics between species, mainly in pigmentation patterns. Larvae were obtained by zooplankton tows in 3 oceanographic cruises in the southern Gulf of California and adjacent waters. The presence of A. thazard and A. rochei larvae was genetically confirmed. The sequences of 7 larvae showed genetic divergences lower than 1% when were compared to sequences of A. thazard adults, while 15 larvae showed genetic divergences lower than 2% when where compared to sequences of A. rochei adults. Genetic divergences between both Auxis species were higher than 2%. These results suggest the spawning of both species in the Gulf of California. On the other hand, pigmentation patterns and morphometric characteristics, in all larval stages, did not permit the secure differentiation between species. Thus, the use of molecular identification by COI is recommended to identify Auxis larvae to the species level, as well as in other marine fish larvae collected in other regions of the world, that have identification troubles

Pensamiento Novohispano 20

El presente libro reúne 26 trabajos de investigación que tienen como objetivo mantener viva la relación cultural del presente con nuestro pasado histórico. Partimos del hecho de que somos seres históricos, es decir, pensamos y reconocemos la historia como parte constitutiva de nuestra existencia vital, razón que viene a consolidar el estudio y la investigación de nuestro pasado. El sentido que fortalece cada una de las colaboraciones aquí presentadas se convierte en un homenaje a la memoria histórica que recupera los hechos “pequeños”, los aparentemente “insignificantes”, para clarificar la “grandes” intervenciones. Cada uno de los trabajos aquí expuestos tiene el propósito de contribuir al estudio y difusión de la cultura novohispana.El número 20 de Pensamiento Novohispano ha quedado integrado por 26 trabajos de investigación distribuidos de la siguiente manera: 11 corresponden al siglo xvi; 5 al siglo XVII y 10 al siglo XVIII. Como en números anteriores, la diversidad de temas sigue presente, pues es una característica de este libro, que busca mantener viva la relación cultural de nuestro pasado histórico con el presente. Partimos del hecho de que somos seres históricos, es decir, pensamos y reconocemos la historia como parte constitutiva de nuestra existencia vital, razón que viene a consolidar el estudio y la investigación de nuestro pasado